1 //===-- PPCTargetObjectFile.cpp - PPC Object Info -------------------------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9
10 #include "PPCTargetObjectFile.h"
11 #include "llvm/IR/Mangler.h"
12 #include "llvm/MC/MCContext.h"
13 #include "llvm/MC/MCExpr.h"
14 #include "llvm/MC/MCSectionELF.h"
15
16 using namespace llvm;
17
18 void
19 PPC64LinuxTargetObjectFile::
Initialize(MCContext & Ctx,const TargetMachine & TM)20 Initialize(MCContext &Ctx, const TargetMachine &TM) {
21 TargetLoweringObjectFileELF::Initialize(Ctx, TM);
22 InitializeELF(TM.Options.UseInitArray);
23 }
24
SelectSectionForGlobal(const GlobalValue * GV,SectionKind Kind,Mangler & Mang,const TargetMachine & TM) const25 const MCSection *PPC64LinuxTargetObjectFile::SelectSectionForGlobal(
26 const GlobalValue *GV, SectionKind Kind, Mangler &Mang,
27 const TargetMachine &TM) const {
28 // Here override ReadOnlySection to DataRelROSection for PPC64 SVR4 ABI
29 // when we have a constant that contains global relocations. This is
30 // necessary because of this ABI's handling of pointers to functions in
31 // a shared library. The address of a function is actually the address
32 // of a function descriptor, which resides in the .opd section. Generated
33 // code uses the descriptor directly rather than going via the GOT as some
34 // other ABIs do, which means that initialized function pointers must
35 // reference the descriptor. The linker must convert copy relocs of
36 // pointers to functions in shared libraries into dynamic relocations,
37 // because of an ordering problem with initialization of copy relocs and
38 // PLT entries. The dynamic relocation will be initialized by the dynamic
39 // linker, so we must use DataRelROSection instead of ReadOnlySection.
40 // For more information, see the description of ELIMINATE_COPY_RELOCS in
41 // GNU ld.
42 if (Kind.isReadOnly()) {
43 const GlobalVariable *GVar = dyn_cast<GlobalVariable>(GV);
44
45 if (GVar && GVar->isConstant() &&
46 (GVar->getInitializer()->getRelocationInfo() ==
47 Constant::GlobalRelocations))
48 Kind = SectionKind::getReadOnlyWithRel();
49 }
50
51 return TargetLoweringObjectFileELF::SelectSectionForGlobal(GV, Kind,
52 Mang, TM);
53 }
54
55 const MCExpr *PPC64LinuxTargetObjectFile::
getDebugThreadLocalSymbol(const MCSymbol * Sym) const56 getDebugThreadLocalSymbol(const MCSymbol *Sym) const {
57 const MCExpr *Expr =
58 MCSymbolRefExpr::Create(Sym, MCSymbolRefExpr::VK_PPC_DTPREL, getContext());
59 return MCBinaryExpr::CreateAdd(Expr,
60 MCConstantExpr::Create(0x8000, getContext()),
61 getContext());
62 }
63
64